It is know that the outer diameter of the spout of such a nozzle in practice has a value which depends on the fuel distributed. Thus, the spout of a nozzle belonging to a pump supplying diesel or leaded petrol has a greater diameter than the spout of a nozzle belonging to a pump supplying lead-free petrol.
Various measures are known, in particular from the French patent 2 244 344, which are taken such that the end piece of the filler pipe of a vehicle using lead-free petrol cannot accept the spout of a supply nozzle of a diesel or leaded petrol pump; such a spout, due to its diameter being greater that that of a spout for lead-free petrol, cannot enter into an aperture dimensioned for that purpose.
Various measures, in particular from the European patents 1 262 355, 1 262 356, 1 284 212 and 1 319 545, are known for solving the converse problem, i.e. preventing a nozzle spout from a lead-free petrol pump entering a filler end piece for a diesel vehicle.